on seas, sandy deserts,
or at best barren steppes; here, and here only, was there a rich prize
close at hand and (as it seemed) only waiting to be grasped.

But if the aggressive force of Persia was to be turned in this
direction, if the stream of conquest was to be set westward along the
flanks of Rhodope and Haemus, it was essential to success, and even to
safety, that the line of communication with Asia should remain intact.
Now, there lay on the right flank of an army marching into Europe a vast
and formidable power, known to be capable of great efforts, which, if
allowed to feel itself secure from attack, might be expected at any
time to step in, to break the line of communication between the east
and west, and to bring the Persians who should be engaged in conquering
Pseonia, Macedonia, and Greece, into imminent danger. It is greatly to
the credit of Darius that he saw this peril--saw it and took effectual
measures to guard against it. The Scythian expedition was no insane
project of a frantic despot, burning for revenge, or ambitious of an
impossible conquest. It has all the appearance of being a well-laid
plan, conceived by a moderate and wise prince, for the furtherance of
a great design, and the permanent advantage of his empire. The lord of
South-Western Asia was well aware of the existence beyond his northern
frontier of a standing menace to his power. A century had not sufficed
to wipe out the recollection of that terrible time when Scythian hordes
had carried desolation far and wide over the fairest of the regions that
were now under the Persian dominion. What had occurred once might recur.
Possibly, as a modern author suggests, "the remembrance of ancient
injuries may have been revived by recent aggressions." It was at any
rate essential to strike terror into the hordes of the Steppe Region in
order that Western Asia might attain a sense of security. It was still
more essential to do so if the north-west was to become the scene
of war, and the Persians were to make a vigorous effort to establish
themselves permanently in Europe. Scythia, it must be remembered,
reached to the banks of the Danube. An invader, who aspired to the
conquest even of Thrace, was almost forced into collision with her next
neighbor.

Darius, having determined on his course, prefaced his expedition by a
raid, the object of which was undoubtedly to procure information. He
ordered Ariaramnes, satrap of Cappadocia, to cross the Euxin